1KSMB68 Equivalent & Substitute Parts

Part Overview

The 1KSMB68 is a unidirectional Transient Voltage Suppressor (TVS) diode manufactured by Littelfuse Inc., designed for general-purpose overvoltage protection in surface-mount applications. The device features a 58.1V reverse standoff voltage with 96.6V maximum clamping voltage and 10.9A peak pulse current capability in a DO-214AA (SMB) package. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility for new designs and production continuity.

Key Parameters

Parameter	Value	Unit
Voltage - Reverse Standoff (Typ)	58.1	V
Voltage - Breakdown (Min)	61.2	V
Voltage - Clamping (Max) @ Ipp	96.6	V
Current - Peak Pulse (10/1000µs)	10.9	A
Power - Peak Pulse	1000	W
Operating Temperature Range	-55 to 150	°C
Package / Case	DO-214AA, SMB	-
Mounting Type	Surface Mount	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution of the 1KSMB68 is determined by the following critical electrical parameters: reverse standoff voltage (58.1V typical), breakdown voltage range (61.2V minimum), maximum clamping voltage, peak pulse current rating, and power dissipation capability. All substitute parts must maintain the same DO-214AA (SMB) surface-mount package to ensure mechanical and thermal compatibility with existing PCB layouts and assembly processes.

The substitute parts are grouped based on their adherence to these core parameters:

Group 1 - Direct Electrical Equivalents: Parts with 58.1V reverse standoff voltage, similar clamping voltage performance (92-96.6V range), and comparable peak pulse current (6.6-10.9A) in active product status.

Group 2 - Voltage-Matched Alternatives: Parts maintaining the 58.1V standoff voltage specification with acceptable variations in clamping voltage and current ratings, suitable for applications where exact electrical performance is not critical.

Group 3 - Package-Compatible Alternatives: Parts in DO-214AA (SMB) package with active status but with electrical parameters outside the primary specification range, applicable only where circuit design permits voltage or current derating.

Parameter Comparison

Part Number	Manufacturer	Product Status	Voltage - Reverse Standoff (V)	Voltage - Clamping (Max) @ Ipp (V)	Current - Peak Pulse (A)	Power - Peak Pulse (W)	Operating Temp (°C)	Package
1KSMB68	Littelfuse Inc.	Obsolete	58.1	96.6	10.9	1000	-55 to 150	DO-214AA (SMBJ)
1KSMB68A	Taiwan Semiconductor Corporation	Active	58.1	92	10.9	1000	-55 to 175	DO-214AA (SMB)
SM6T68AY	STMicroelectronics	Active	58.1	121	33 (8/20µs)	600	-55 to 150	DO-214AA (SMB)
SMBJP6KE68A-TP	Micro Commercial Co	Active	58.1	92	6.6	600	-55 to 175	DO-214AA (SMBJ)
TVP06B680A-G	Comchip Technology	Active	-	-	-	600	-55 to 150	DO-214AA (SMB)
P6SMB68A	Eaton - Electronics Division	Active	5.8	10.5	58.1	600	-55 to 150	DO-214AA (SMB)

Engineering Selection Recommendations

Primary Substitute - 1KSMB68A (Taiwan Semiconductor Corporation): This part is the closest electrical equivalent with active product status. It maintains the 58.1V reverse standoff voltage and 10.9A peak pulse current specification. The clamping voltage is 4.6V lower (92V vs 96.6V), which is within acceptable tolerance for most general-purpose protection circuits. Extended operating temperature range (-55 to 175°C vs -55 to 150°C) provides additional thermal margin. ROHS3 compliance and unlimited moisture sensitivity level ensure compatibility with modern manufacturing processes.

Secondary Substitute - SM6T68AY (STMicroelectronics): Maintains 58.1V standoff voltage with active status and AEC-Q101 automotive qualification. Higher clamping voltage (121V) and peak pulse current (33A at 8/20µs) indicate enhanced protection capability suitable for higher-energy transient environments. Reduced power rating (600W vs 1000W) requires circuit-level evaluation. Automotive-grade qualification provides additional reliability assurance for critical applications.

Tertiary Substitute - SMBJP6KE68A-TP (Micro Commercial Co): Maintains 58.1V standoff voltage and 92V clamping voltage with active status. Reduced peak pulse current (6.6A vs 10.9A) and power rating (600W vs 1000W) limit application scope to lower-energy transient protection. Extended operating temperature range (-55 to 175°C) is advantageous. Suitable for applications where transient energy levels are lower than original design specification.

Not Recommended - P6SMB68A (Eaton): Voltage specifications (5.8V standoff, 10.5V clamping) are fundamentally incompatible with the 1KSMB68 design intent. This part operates in a different voltage protection class and cannot serve as a direct substitute.

Insufficient Data - TVP06B680A-G (Comchip Technology): Critical electrical parameters (standoff voltage, breakdown voltage, clamping voltage, peak pulse current) are not provided. Selection of this part requires complete datasheet specification verification before implementation.

Frequently Asked Questions (FAQ)

Q: Can 1KSMB68A directly replace 1KSMB68 in existing designs?

A: Yes, with circuit-level verification. The 1KSMB68A maintains the critical 58.1V reverse standoff voltage and 10.9A peak pulse current. The 4.6V reduction in clamping voltage (92V vs 96.6V) is typically acceptable for general-purpose protection but should be confirmed against circuit transient voltage limits. Both parts use identical DO-214AA (SMB) packaging for mechanical compatibility.

Q: What is the significance of the clamping voltage difference between 1KSMB68 (96.6V) and 1KSMB68A (92V)?

A: Clamping voltage determines the maximum voltage presented to protected circuitry during a transient event. The 4.6V difference represents approximately 4.8% variation. For circuits designed with 96.6V clamping margin, the lower 92V clamping of 1KSMB68A provides slightly tighter protection. Verify that downstream components can tolerate 92V without degradation.

Q: Why does SM6T68AY have higher peak pulse current (33A) than the original 1KSMB68 (10.9A)?

A: SM6T68AY uses a different pulse waveform specification (8/20µs vs 10/1000µs). The 8/20µs waveform is shorter duration, resulting in higher peak current for equivalent energy dissipation. The 600W power rating (vs 1000W) indicates lower total energy handling. These parts address different transient profiles and require application-specific evaluation.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All active substitute parts listed (1KSMB68A, SM6T68AY, SMBJP6KE68A-TP, TVP06B680A-G) carry ROHS3 compliance certification, ensuring compatibility with modern manufacturing and environmental regulations.

Q: What is the impact of operating temperature range differences?

A: The original 1KSMB68 operates -55 to 150°C. Substitutes 1KSMB68A and SMBJP6KE68A-TP extend to 175°C, providing 25°C additional thermal margin. SM6T68AY and TVP06B680A-G maintain the -55 to 150°C range. Extended temperature range is beneficial for high-ambient or high-power applications but does not affect substitution validity for standard temperature environments.

Q: Can P6SMB68A be used as a substitute?

A: No. P6SMB68A operates at 5.8V standoff voltage with 10.5V clamping, representing a different voltage protection class entirely. This part is designed for low-voltage applications and cannot protect circuits designed for 58.1V standoff protection.

Q: What packaging considerations apply to these substitutes?

A: All listed substitutes use DO-214AA (SMB or SMBJ variant) surface-mount packages, ensuring direct PCB footprint compatibility. SMBJ and SMB designations refer to lead configuration variants within the same DO-214AA envelope. Verify specific lead configuration against PCB design files, though both variants are mechanically interchangeable in standard SMB footprints.

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